Parent and Guarantor Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Statement of Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	$ 1,647	$ 1,447	$ 3,190	$ 2,815
Interest and Fee Income, Loans and Leases Held-for-sale	6	0	6	0
Interest and Dividend Income, Securities, Operating	188	146	364	280
Interest Income, Deposits with Financial Institutions	17	7	32	12
Operating Leases, Income Statement, Lease Revenue	374	488	756	1,031
Total financing revenue and other interest income	2,232	2,088	4,348	4,138
Interest Expense, Deposits	399	250	750	481
Interest Expense, Short-term Borrowings	40	33	72	60
Interest Expense, Long-term Debt	434	417	845	841
Interest Expense, Related Party	0	0	0	0
Interest Expense	873	700	1,667	1,382
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	265	321	538	710
Net Financing Revenue	1,094	1,067	2,143	2,046
Dividends from Bank Subsidiary	0		0
Dividends From Non Bank Subsidiary	0	0	0	0
Insurance Services Revenue	239	227	495	468
Gain (Loss) on Sales of Loans, Net	1	36	2	50
Gain (Loss) on Investments	27	23	15	50
Noninterest Income, Other Operating Income	97	102	206	216
Nonoperating Income (Expense)	364	388	718	784
Revenues	1,458	1,455	2,861	2,830
Provision for Loan Losses Expensed	158	269	419	540
Labor and Related Expense	292	265	598	550
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	101	125	164	213
Other Noninterest Expense	446	420	891	825
Noninterest Expense	839	810	1,653	1,588
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	461	376	789	702
Income Tax Expense (Benefit)	113	122	189	235
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	348	254	600	467
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	1	(2)	(1)	(1)
Undistributed income of bank subsidiaries	0	0	0	0
Undistributed income of nonbank subsidiaries	0	0	0	0
Net Income (Loss) Attributable to Parent	349	252	599	466
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(70)	76	(398)	96
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	279	328	201	562
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	(1)	(35)	10	(70)
Interest and Fee Income, Loans and Leases Held-for-sale	0		0
Interest and Dividend Income, Securities, Operating	0	0	0	0
Interest Income, Deposits with Financial Institutions	2	2	4	4
Operating Leases, Income Statement, Lease Revenue	1	3	3	6
Total financing revenue and other interest income	8	(27)	27	(53)
Interest Expense, Deposits	0	1	0	2
Interest Expense, Short-term Borrowings	10	19	20	36
Interest Expense, Long-term Debt	257	274	515	556
Interest Expense, Related Party	4	4	7	8
Interest Expense	271	298	542	602
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	1	3	5	5
Net Financing Revenue	(264)	(328)	(520)	(660)
Dividends from Bank Subsidiary	500		1,500
Dividends From Non Bank Subsidiary	132	387	301	427
Insurance Services Revenue	0	0	0	0
Gain (Loss) on Sales of Loans, Net	0	32	28	30
Gain (Loss) on Investments	0	0	0	0
Noninterest Income, Other Operating Income	100	163	196	431
Nonoperating Income (Expense)	100	195	224	461
Revenues	468	254	1,505	228
Provision for Loan Losses Expensed	32	82	113	189
Labor and Related Expense	25	19	48	140
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	0	0	0	0
Other Noninterest Expense	173	213	355	501
Noninterest Expense	198	232	403	641
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	238	(60)	989	(602)
Income Tax Expense (Benefit)	(66)	(93)	(122)	(227)
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	304	33	1,111	(375)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	(1)	0	(2)	2
Undistributed income of bank subsidiaries	52	375	(545)	764
Undistributed income of nonbank subsidiaries	(6)	(156)	35	75
Net Income (Loss) Attributable to Parent	349	252	599	466
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(70)	76	(398)	96
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	279	328	201	562
Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	0	0	0	0
Interest and Fee Income, Loans and Leases Held-for-sale	0		0
Interest and Dividend Income, Securities, Operating	0	0	0	0
Interest Income, Deposits with Financial Institutions	0	0	0	0
Operating Leases, Income Statement, Lease Revenue	0	0	0	0
Total financing revenue and other interest income	0	0	0	0
Interest Expense, Deposits	0	0	0	0
Interest Expense, Short-term Borrowings	0	0	0	0
Interest Expense, Long-term Debt	0	0	0	0
Interest Expense, Related Party	0	0	0	0
Interest Expense	0	0	0	0
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	0	0	0	0
Net Financing Revenue	0	0	0	0
Dividends from Bank Subsidiary	500		1,500
Dividends From Non Bank Subsidiary	0	0	0	0
Insurance Services Revenue	0	0	0	0
Gain (Loss) on Sales of Loans, Net	0	0	0	0
Gain (Loss) on Investments	0	0	0	0
Noninterest Income, Other Operating Income	0	0	0	0
Nonoperating Income (Expense)	0	0	0	0
Revenues	500	0	1,500	0
Provision for Loan Losses Expensed	0	0	0	0
Labor and Related Expense	0	0	0	0
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	0	0	0	0
Other Noninterest Expense	0	0	0	0
Noninterest Expense	0	0	0	0
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	500	0	1,500	0
Income Tax Expense (Benefit)	0	0	0	0
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	500	0	1,500	0
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	0	0	0	0
Undistributed income of bank subsidiaries	52	375	(545)	764
Undistributed income of nonbank subsidiaries	0	0	0	0
Net Income (Loss) Attributable to Parent	552	375	955	764
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(56)	50	(332)	55
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	496	425	623	819
Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	1,648	1,482	3,180	2,885
Interest and Fee Income, Loans and Leases Held-for-sale	6		6
Interest and Dividend Income, Securities, Operating	188	146	365	281
Interest Income, Deposits with Financial Institutions	14	5	28	8
Operating Leases, Income Statement, Lease Revenue	373	485	753	1,025
Total financing revenue and other interest income	2,232	2,122	4,338	4,206
Interest Expense, Deposits	395	249	750	479
Interest Expense, Short-term Borrowings	30	14	52	24
Interest Expense, Long-term Debt	177	143	330	285
Interest Expense, Related Party	8	3	10	7
Interest Expense	610	409	1,142	795
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	264	318	533	705
Net Financing Revenue	1,358	1,395	2,663	2,706
Dividends from Bank Subsidiary	0		0
Dividends From Non Bank Subsidiary	0	0	0	0
Insurance Services Revenue	239	227	495	468
Gain (Loss) on Sales of Loans, Net	1	4	2	20
Gain (Loss) on Investments	27	23	15	50
Noninterest Income, Other Operating Income	185	210	406	433
Nonoperating Income (Expense)	452	464	918	971
Revenues	1,810	1,859	3,581	3,677
Provision for Loan Losses Expensed	126	187	334	351
Labor and Related Expense	267	246	550	410
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	101	125	164	213
Other Noninterest Expense	461	478	932	972
Noninterest Expense	829	849	1,646	1,595
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	855	823	1,601	1,731
Income Tax Expense (Benefit)	179	215	311	462
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	676	608	1,290	1,269
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	2	(2)	1	(3)
Undistributed income of bank subsidiaries	0	0	0	0
Undistributed income of nonbank subsidiaries	0	0	0	0
Net Income (Loss) Attributable to Parent	678	606	1,291	1,266
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(74)	72	(413)	91
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	604	678	878	1,357
Affiliated Entity [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	0	0	0	0
Interest Income, Deposits with Financial Institutions	0	0	0	0
Gain (Loss) on Sales of Loans, Net			0	0
Affiliated Entity [Member] | Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	4	3	6	7
Interest Income, Deposits with Financial Institutions	2	0	4	0
Gain (Loss) on Sales of Loans, Net			83	1,864
Affiliated Entity [Member] | Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	0	0	0	0
Interest Income, Deposits with Financial Institutions	0	0	0	0
Gain (Loss) on Sales of Loans, Net			0	0
Affiliated Entity [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	1	2	2	4
Interest Income, Deposits with Financial Institutions	2	2	4	3
Gain (Loss) on Sales of Loans, Net			(5)	246
Consolidation, Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	0	0	0	0
Interest and Fee Income, Loans and Leases Held-for-sale	0		0
Interest and Dividend Income, Securities, Operating	0	0	(1)	(1)
Interest Income, Deposits with Financial Institutions	1	0	0	0
Operating Leases, Income Statement, Lease Revenue	0	0	0	0
Total financing revenue and other interest income	(8)	(7)	(17)	(15)
Interest Expense, Deposits	4	0	0	0
Interest Expense, Short-term Borrowings	0	0	0	0
Interest Expense, Long-term Debt	0	0	0	0
Interest Expense, Related Party	(12)	(7)	(17)	(15)
Interest Expense	(8)	(7)	(17)	(15)
Operating Leases, Income Statement, Depreciation Expense on Property Subject to or Held-for-lease	0	0	0	0
Net Financing Revenue	0	0	0	0
Dividends from Bank Subsidiary	(1,000)		(3,000)
Dividends From Non Bank Subsidiary	(132)	(387)	(301)	(427)
Insurance Services Revenue	0	0	0	0
Gain (Loss) on Sales of Loans, Net	0	0	(28)	0
Gain (Loss) on Investments	0	0	0	0
Noninterest Income, Other Operating Income	(188)	(271)	(396)	(648)
Nonoperating Income (Expense)	(188)	(271)	(424)	(648)
Revenues	(1,320)	(658)	(3,725)	(1,075)
Provision for Loan Losses Expensed	0	0	(28)	0
Labor and Related Expense	0	0	0	0
Liability for Unpaid Claims and Claims Adjustment Expense, Incurred Claims	0	0	0	0
Other Noninterest Expense	(188)	(271)	(396)	(648)
Noninterest Expense	(188)	(271)	(396)	(648)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest	(1,132)	(387)	(3,301)	(427)
Income Tax Expense (Benefit)	0	0	0	0
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	(1,132)	(387)	(3,301)	(427)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	0	0	0	0
Undistributed income of bank subsidiaries	(104)	(750)	1,090	(1,528)
Undistributed income of nonbank subsidiaries	6	156	(35)	(75)
Net Income (Loss) Attributable to Parent	(1,230)	(981)	(2,246)	(2,030)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	130	(122)	745	(146)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	(1,100)	(1,103)	(1,501)	(2,176)
Consolidation, Eliminations [Member] | Affiliated Entity [Member]
Condensed Income Statements, Captions [Line Items]
Interest and Fee Income, Loans and Leases	(5)	(5)	(8)	(11)
Interest Income, Deposits with Financial Institutions	$ (4)	$ (2)	(8)	(3)
Gain (Loss) on Sales of Loans, Net			$ (78)	$ (2,110)